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Re: [PATCH 2/6] mm: Add vm_insert_pfn_prot

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On Thu, 10 Dec 2015 19:21:43 -0800 Andy Lutomirski <luto@kernel.org> wrote:

> The x86 vvar mapping contains pages with differing cacheability
> flags.  This is currently only supported using (io_)remap_pfn_range,
> but those functions can't be used inside page faults.

Foggy.  What does "support" mean here?

> Add vm_insert_pfn_prot to support varying cacheability within the
> same non-COW VMA in a more sane manner.

Here, "support" presumably means "insertion of pfns".  Can we spell all
this out more completely please?

> x86 needs this to avoid a CRIU-breaking and memory-wasting explosion
> of VMAs when supporting userspace access to the HPET.
> 

OtherwiseAck.
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Thread

[PATCH 0/6] mm, x86/vdso: Special IO mapping improvements Andy Lutomirski <luto@kernel.org> - 2015-12-11 04:30 +0100
  [PATCH 4/6] x86,vdso: Use .fault for the vdso text mapping Andy Lutomirski <luto@kernel.org> - 2015-12-11 04:30 +0100
  [PATCH 5/6] x86,vdso: Use .fault instead of remap_pfn_range for the vvar mapping Andy Lutomirski <luto@kernel.org> - 2015-12-11 04:30 +0100
  [PATCH 6/6] x86/vdso: Disallow vvar access to vclock IO for never-used vclocks Andy Lutomirski <luto@kernel.org> - 2015-12-11 04:30 +0100
  [PATCH 2/6] mm: Add vm_insert_pfn_prot Andy Lutomirski <luto@kernel.org> - 2015-12-11 04:30 +0100
    Re: [PATCH 2/6] mm: Add vm_insert_pfn_prot Andrew Morton <akpm@linux-foundation.org> - 2015-12-11 23:40 +0100
      Re: [PATCH 2/6] mm: Add vm_insert_pfn_prot Andy Lutomirski <luto@amacapital.net> - 2015-12-11 23:50 +0100
  [PATCH 1/6] mm: Add a vm_special_mapping .fault method Andy Lutomirski <luto@kernel.org> - 2015-12-11 04:30 +0100
    Re: [PATCH 1/6] mm: Add a vm_special_mapping .fault method Andrew Morton <akpm@linux-foundation.org> - 2015-12-11 23:30 +0100
      Re: [PATCH 1/6] mm: Add a vm_special_mapping .fault method Ingo Molnar <mingo@kernel.org> - 2015-12-14 10:20 +0100

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